Burglar alarm



C. L. GRAEF BURGLAR ALARM Filed March 21. 1922 Patented (Get. 235, 1923.,

CARL Id- GRAEF, OF HAWTHORNE, NEXV JERSEY, .SSSIGNOBJ ONE-HALF TO HERMANN KIND, OF YORK, N. Y.

BURGLAB ALARM".

Application filed March 21, 1922.

To all whom it may concern:

Be it known that I, CARL L. Gunner, a citizen of the United States, and resident of Hawthorne, county of Passaic, and State Of New Jersey, have invented certain new and useful Improvements in Burglar Alarms, of which the following is a specification.

This invention relates to devices adapted for use as a burglar alarm, and particularly to those of the type usedon doors.

Burglar alarms'for use on doors as heretofore' proposed have, so far as applicant is aware, been open to the objection either that they comprised members which require to be attached to the body of the door, or are so constructed that the alarm given by them can be minimized by manipulation of the door knob by a person endeavoring surreptitiously to open the door. Devices subject to the first-mentioned objection are not readily portable, that is, they cannot be easily changed from one door to another, and the attachment and detachment of the devices to and from the door cause it to be defaced, whereas devices subject to the last named objection do not afford the security and protection which they are intended to provide. It is an object of this invention to provide a device for use as a burglar alarm which can be very cheaply constructed, which can be readily attached toand detached from a door without defacing it, and which will give vigorous and continuous alarm entirely out of the control of a person outside of the door.

To this end an important feature of the invention resides in the pro-vision of a device comprising sounding means constructed to act continuously after its operation is once initiated, and means for controlling the operation of the soundingineans.

A further feature of the invention resides in the provision of a member constructed for attachment to a door knob. and sounding means carried by said member and rendered operative by a trip device upon turning of the door knob to open the door.

Other objects and features of the invention will appear as the description proceeds, and will be pointed out in the appended claims.

In the drawing in which like reference Serial No. 545,563.

characters indicate identical parts inthe various views:

Fig. l is a view of the device in front elevation and in set position;

Fig. 2 is a side elevation of the device looking from the right in Fig. 1;

Fig. 3 is .a front elevation of the device partly in section and in positionto give an alarm;

Fig. 4c is a detail view taken from the bottom of the disk which carries the dome of the bell and its actuating wheels;

Fig. 5 is a'detail view of the housing for the bell operating spring, and

Fig. 6 is a view in front elevation of a modified form of the invention.

The illustrated construction comprises generally anchor member 2 constructed for attachment to a door knob and a pendant member 4 which carries the sounding means, preferably in the form of a bell, and means for controlling the operation of the bell.

As shown, the anchor member 2 is substantially barrel-shaped, the open end 6 of the member being adapted to be passed over a door knob. Secured within the anchor member 2 is a clamping ring 8 provided at its upper ends with ears 10 projecting upwardly through the slot 12 in the. top part of the anchor member, and threadee into the earsv 10 of the clamping ring is a thumb screw 14. The ring 8 is of less diameter than the barrel portion of the anchor member so as to enable it to be adjusted to door knobs of varying sizes, and is secured at its lower intermediate portion to the barrel of the anchor member by suitable fastening means, such as, for exan'iple, a rivet 16. The anchor member 2 and the clamping ring 8 are preferably concaved on their inner surfaces to conform with the usual shape of door knobs. It will be understood from the foregoing that the anchor member 2 is fixedly secured to the door knob so as toturn with it.

' The pendant member 4- comprises a shank portion 18 of rectangular transverse section and an enlarged substantially circular portion 20 within which the bell, designated generally by the numeral 22, is mounted.

The bell comprises a barrel-shaped member 24: upon the bottom of which is secured a saddle member provided at its ends with threaded openings adapted to receive screws for securing the bell to the base of 'the pendant member 4. Secured upon the 5 barrel member 24 after the manner of a cover therefor is a disk 26 upon the under surface of which is a coil spring'27 housed in the barrel member 24. The disk 26 may be secured upon the member 24 in any sultable manner, as by means of tongues 30 extending upwardly from the rim of the me1n ber 24, and received in notches 32 of the disk 26. The coil spring 27 at its inner end is connected .with a 'post 34 journaled in the disk 26 and in a plate 36 located above the disk 26 and connected to it by posts 38. The coil spring 27 is connected at its outer end to a post 39 depending from the disk 26, and is held against displacement in the plane of the disk'26 by a leaf spring 40 extending downwardly from the lower surface of the disk.

Between the plate 36 and the disk 26 the post 34 is provided with a pinion 41 and loosely held on the post 34 is a relatively large pinion 42 having a pawl 44 fulcrumed r thereon and urged into engagement with the teeth on the pinion 41 by a leaf spring 46 soldered or otherwise secured to the pin ion 42% its end remote from the pawl 44.

The pinion 42 on the post 34 meshes with a small pinion 48 on a pintle 5O journaled in the disk 26 and the plate 36. The pintle 50 is also provided with a larger pinion 52 which meshes in turn with a small pinion 54 also journaled in the disk 26 and the plate 36, and having associated with it a largerpinion 56. gThe dome 58 of the bell is threaded upon the upper end of the post 34 andis arranged to co-act with a hammer 60 carried at one end of a leaf spring 62, the other end of which is soldered or otherwise secured to a double-ended pawl 66 positioned for operation by the pinion 56.

after thebell. has been threaded upon the post 34 far enough to seat it upon the post,

'continued'rotation of the bell in the same direction, that is, clockwise, as shown in Fig. 3, causes the post 34 to be rotated to wind up the coil spring 27. During such rotation of the post 34 and the dome 58 of the bell, the teeth of the pinion 41 on the post 84-slide past the pawl 44 so that the pinion wheels driven from the pinion 42 are not rotated and the bell is not rung. Upon release of the dome, however, the coil'spring 27 will rotate the post 34 in the reverse direction, and the movement of the post 34 in such direction will betransmitted by the pawl 44 to the pinion 42 and then throughthe otherpinions to the pinion 56, causing such pinion to be rotated in a contra-clockwise direction. Upon rotation of the pmion 56 the teeth of the pinion engage the With the construction thus far described,

end 68 of the double-ended pawl 66 and thereby impel the hammer 60 outwardly to strike the dome 58 of the bell. on the pinion 56 are so related to the endsof the pawl 66 as to cause them to engage the opposite end of the pawl between each two successive engagements with theend 68 so as to retract the hammer 60 from the dome 58.

The means for controlling the operation of the bell comp-rises a trip rod 70 fitted slidably in bearings 72 and 74 in, the shank The teeth portion 18 of the pendant member 4'. The

trip rod 70 is formed, as most clearly shown in Fig. 2, with an offset nose 76 adapted for engagement with the end 68' of the pawl '66, as seen in Fig-1, to prevent the hammer 6O from being moved outwardly against the dome of the bell, thereby preventing the bell gagement of the nose 76 of the trip rod with the pawl 66, the disk 26 and the barrel cordingly constitutes a pivotal connection,

between the anchor member 2 and the pendant member 4. The trip rod 70 between the from ringing. In order "to permit such en portion 24of the bell are provided withbearings 72 and 74 is provided with a pin 90- and interposed between the pin 90 and the bearing 74 is an expansive spring 92 which tends normally to move the trip rod 70 to its uppermost position in which the nose 7 6 is disengaged from the pawl 66.. A latch 93 fulcrumed on the pendant member 4 is adapted to engage the pin 90 on the upperside thereof to retain the nose 76 of i the trip rod 1n engagement with the pawl 66, said latch being formed with. a lateral finger piece 94 extending through a slot95 in the front face of the member 4.: The" bracket 88- is provided between the ears 86 with a cam abutment surface 96which i so related to the pivot pin 84 that when the triprod 70 is pushed down and the latch 93 is engaged with the pin 90 on the trip rod, the'upper end of the trip rod may pass he neath the abutment surface, shown in Fig. 1, and the weight. of the pendant member 4 and the parts carried by it is such that said member upon rotation of the anchor member 2 is caused to turn about the pivot pin 84 so as to retain its vertical position; in consequence of which theupper end of the trip rod "('0 is carried, out of engage.

ment'with the abutment'surface -96'of the anchor member. The dependant member 4 is pivoted to thebracket 88 below the cam i 96 thereof so that the swing of said member 2 has greater leverage for disengaging id mo oam.

The manner of use of the illustrated device is as follows:

Assuming that the parts are in the positions shown in Fig. 3 and the anchor member 2 is attached to a door knob, the trip rod 70 may be pushed downwardly and the latch 93 engaged with the pin 90 on the rod. The parts will then be moved automatically under the action of gravity to the position shown in Fig. 1, in which the upper end of the trip rod 70 aligns with the abutment surface 96 on the bracket 88 of the anchor member. If it is not desired that the device shall be immediately set for use the latch 93 may be left in engagement with the pin 90, and in such position of the parts no alarm will be given upon turning of the knob. When it is desired to set the device the finger piece 94: on the latch 93 is merely pushed to the right, as shown in Fig. 1, thereby releasing the trip rod and causing it to be pressed by the spring 92 against the abutment surface 96. "in such position of the parts the abutment surface 96 retains the nose 76 ot' the trip rod in engagement with the end 68 of the pawl 66, thus preventin the bell from ringing. When, however, t e knob is turned, the tendency of the pendant member 1 to retain by gravity its vertical position, permits the abutment 96 to be turned out of engagement with the trip rod 70. Then the expansive spring 92 pushes said rod upward and withdraws the lower end thereof from engagement with the pawl 66 and said pawl actuates the striker and causes the bell to ring.

In the form of the invention shown in Fig. 6 the bell 100 is of a conventional electric type and the pendant member 1 is provided at its shank portion with a fixed contact member 102 arranged for engagement with a movable contact member 10% carried by and suitably insulated from the trip rod A suitable source of electric current, illustrated diagrammatically at 106, is connected at one side by a conductor 108 to the contact member 102. A second conductor 110 is connected at one end to the contact member 104 and passes through a slot in the member 41. At its other end the conductor 110 is connected to a binding post 112 or" the bell, and the other binding post 11 1 of the bell is connected by a conductor 116 to the source of electric current 106. The source 01: electric current 106 may, for example, consist of dry cells.

In the use of the modified construction shown in Fig. 6 it will be understood that when the rod 70 is tripped by turning of the door knob and the anchor member 2, the members 102 and 104: will be brought into contact with each other, thus completing an electric current through the bell and causing it to ring.

From the foregoing description it will be manifest that the burglar alarm of this invention may be installed on and removed from a door without defacing it, and that, if desired, the device may be very easily and quickly changed from one door to another. Moreover, it will be seen that the device is attractive in appearance and interposes little or no obstruction to the turning of the knob from the inside of a door. Accordingly, if desired, it may be left permanently in place on the door knob and may be very readily and set during the night by shifting the latch 93 to the left or right, respectively. It will be also understood that when the operation of the bell has been once initiated the ringing of the bell cannot be discontinued by manipulation of the knob from the outside of the door, so that if the knob is turned after the device has been set, vigorous and prolonged ringing of the bell is assured.

Having fully described the invention, what is claimed is:

I claim:

1. In a door-knob burglar alarm, the combination of an anchor member having a bracket provided with a stop cam and with an arm extending downwardly below said cam, a pendulum member pivoted to said arm below said cam, an alarm bell mounted on said pendulum member, mechanism for actuating said bell, a spring actuated rod slidingly mounted in said pendulum member adapted to engage said cam at its upper end and said bell operating mechanism at its lower end, and provided on its upper end with a slot engaging the pivotal connection between said pendulum member and said arm, and means for locking said rod in a fixed position.

2. In a door-knob burglar alarm, the combination of an anchor member having a bracket provided with a stop cam and with an arm extending below said cam, a pendulum member having a slotted bearing member at its upper end pivotally connected with said arm, an alarm bell mounted on said pendulum member, means for actuating said bell including a double ended lever, a spring actuated trip-rod slidingly mounted in said bearing and provided with a slot engaging the pivotal connection between said pendulum and said arm, the upper end of said trip-rod being adapted to engage said cam and the lower end of said rod being provided with an off-set adapted to engage said double ended lever, and a latch pivoted on said pendulum member adapted to hold said trip-rod against vertical movement relative to said lever.

In testimony that I claim the foregoing as my invention, 1 have signed my name.

i on L. eaanr.

rendered inoperative during the day 

